1. Field of the Invention
The present invention relates to a catalytic reactor for generating a hydrogen-containing synthesis gas from a rich fuel/oxidizing agent mix. Moreover, the invention relates to an operating method for a reactor of this type and to a burner arrangement configured with a reactor of this type.
2. Brief Description of the Related Art
In the case of a burner arrangement, in particular for a gas turbine of a power plant, as is known, for example, from EP 1 265 029 A2, there is always a need to stabilize a flame front which forms in a combustion chamber when the burner arrangement is operating, in order on the one hand to achieve a combustion operation with minimum possible emissions of pollutants and in order on the other hand to prevent the combustion reaction from being extinguished. In particular when the burner arrangement is being run up or in operating states with low loads, a stable flame front is of increased importance, on account of the lower temperatures.
U.S. Pat. No. 5,346,389 has disclosed a catalytic converter which includes a multiplicity of parallel passages, with catalytically active passages and catalytically inactive passages being arranged alternately over the entire cross section of the catalytic converter. This makes it possible for the catalytically active passages to be cooled by the gas flow in the catalytically inactive passages. Then, a heterogeneous combustion reaction can take place in the catalytically active passages, in which more or less fuel of a lean fuel/oxidizing agent mix is converted by complete oxidation. This catalytic converter may be connected upstream of a combustion chamber in order to increase the temperature therein. This allows the homogenous combustion reaction taking place in the combustion chamber to be thermally stabilized.
U.S. Pat. No. 6,358,040 B1 has disclosed a catalytic converter arrangement through which a rich fuel/oxidizing agent mix flows, with the fuel being completely oxidized. The heat which is generated is released direct to an oxidizing agent flow, which downstream of the catalytic converter arrangement is mixed with the rich combustion exhaust gasses and burnt homogenously in a combustion chamber. This measure also increases the temperature of the fuel/oxidizing agent mix fed to the combustion chamber, which thermally stabilizes combustion in the combustion chamber.
To enable the combustion chamber to be operated stably even at low load, it is, moreover, customary to increase the proportion of fuel in the lean fuel/oxidizing agent mix, in order in this way to increase the temperature in the combustion chamber. This allows a temperature level which is sufficiently above an extinction limit, at which the flame in the combustion chamber is extinguished, to be maintained. The shift in the fuel/oxidizing agent mix from lean in the direction of rich, however, leads to increased formation of pollutants in the combustion reaction. In particular, the NOx emission increases.
It is known from EP 0 767 345 A1 to use a hydrogen generator to generate a hydrogen-containing gas from a fuel/oxidizing agent mix and to admix this gas with a fuel/oxidizing agent mix. The hydrogen increases the reactivity of the fuel/oxidizing agent mix, so that it is possible to improve the combustion in a catalytic burner stage. The hydrogen generator used in this process fractionates the associated fuel and thereby generates the hydrogen preferably with the aid of a catalyst. The outlay on apparatus is in this case relatively high.